Fluid pressure brake



Oct. 19 1937. E. E. HEWITT .FLUID PRESSURE BRAKE s Sheets-Shet 1 Filed Feb. 12, 1957 @QIIF INVENTOR ELLIE E. HEWITT BY ATTORNEY E. E. HEWITT FLUID PRESSURE BRAKE Filed Feb. 12, 1937 3 Sheets-Sheet 2 Oct-19, 1937.

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- 66 emu INVENTOR ATTORNEY ELLIS E. H EWITT v Oct. 19, 1937. E. E. HEWITT FLUID PRESSURE BRAKE Filed Feb. 12, 1957 3 Sheets-Sheet 3 l M i; W I64 I62 fi I in WNW 0 I60 I6?) I I 6 90 I 6 52% 5s 27 W8! 84 168 Q 44 24 NW "HT... "Mm\IIW T 55 68 Q Zlo I 15 97 lg '78 Z| I '74 8 2" 5' g 194% I zoz m I87 IZEJZQZLWZU) 1% 2|7 |7o MENTOR m 68 BYELLIS E. HEWITT ATTORN EY Patented Oct. 19, 1937 UNITED STATES PATENT OFFICE FLUID PRESSURE BRAKE Application February 12, 1937, Serial No. 125,385

10 Claims.

This invention relates to fluid pressure brake systems, and particularly to control apparatus for controlling fluid pressure brake equipments of the type employed on safety cars and motor buses.

One well known type of safety car equipment comprises a fluid pressure brake controlled by a self-lapping brake valve device which is operable through the medium of a pedal to effect service applications of the brakes at various degrees of pressure and is automatically operative when the operators foot is removed from the pedal to effect a so-called dead man's emergency application of the brakes, unless a predetermined service application has previously been made, in which case mechanism included in the brake valve device is adapted to suppress the dead mans emergency application of the brakes to permit removal of the operator's foot from the pedal.

20 It is desirable, however, that means be provided for enabling the operator to effect an emergency application of the brakes at any time by moving the brake valve device to an emergency position.

The principal object of my invention is to provide improved means whereby the brake valve device may be operated to effect an emergency application of the brakes when the pedal is moved beyond service position into an emergency 39 position.

Another object of the invention is to provide means which is designed for association with a self-lapping brake valve device of the type embodying mechanism for suppressing dead man's 35 emergency operation thereof following a service application of the brakes, and which means is operative when the brake pedal is moved to an emergency position to render said mechanism ineifective to suppress an emergency applica- 4!) tion of the brakes.

Other objects and advantages of the invention will be apparent in the following more detailed description thereof, taken with reference to the accompanying drawings, wherein;

Fig. 1 is a diagrammatic view, partly in section, of a safety car brake control equipment embodying the invention;

Fig. 2 is an enlarged detail sectional view of the self-lapping brake valve device shown in Fig. 1;

Fig. 3 is a sectional view taken on the line 3-3 of Fig. 2;

Fig. 4 is a fragmentary view taken on the line 4-4 of Fig. 2;

Fig. 5 is an elevational view, partly in secpipe 33.

ed in the'piston 3B and is adapted to engage 45 cylinder II, a sanding device i2, a circuit breaker 10 device 53, a self-lapping brake valve device l4,

and a foot operated. brake pedal device l5. The brake valve device [4 is of the self-lapping type and is similar in construction and operation to that shown and described in the ap-.

plication of David W. Lloyd, Serial No. 698,243, filed November 16, 1933..

As is best shown in Fig. 2 of the drawings, the brake valve device I comprises a pipe bracket I! to which is secured by bolts [9, a main section H] of a casing. A valve section 23 and an emergency piston section 2!, are secured to the main section iii in a suitable manner. The casing sections l8, Zlland 2| define a pressure chamber 23 which is connected through a passage and pipe 24 with the brake cylinder l I, shown in Fig. 1.

l A supply valve 25 is slidably mounted in a suitable bore formed in the valve section 20 for controlling communication between the pres sure chamber 23 and a valve chamber 26 which is connected by way of a passage and pipe 21 with the main reservoir M. A spring 28 is providedfor normally maintaining the supply valve 25 in its seated position as shown in Fig. 2 of the 35.

drawings.

Slidably mounted'in another bore formed in the casing section 29 parallel to that containing the supply valve 25 is a metering piston 30, which is subject to the opposing forces of fluid in the pressure chamber 23 and of a metering spring 3! that is disposed in a chamber 32 communicating with the atmosphere by way of a passage and A release Valve 35 is operativelymounta valve seat 36 carried Within the piston for con trolling communication between the chamber 32 and a valve chamber 3? which is open to the pressure chamber 23 by way of a passage 38. The release valve 35 is normally urged away from the seat 36 by the pressure of a light spring 39 which is interposed between the piston 33 and a flange 4B formed-on a stem 4| of the valve 35 extending into the pressure chamber 23.

For controlling the operation of the supply and release valves 25 and 35, there is provided mechanism comprising spaced levers 44 and 45, which are pivotally connected, intermediate their ends, to a pin 53 which is carried on a plunger 46 that is slidably guided within suitable bores formed in the casing section is as shown in Fig. 2. At one side of the pivot pin 43 the ends of the levers 4 and 45 are connected togetherby means of a pin 58 on'which is mounted aroller 49 that is adapted to engage the end of the stem M of the release valve 35. -At the other side of the pivot pin 43, the ends of the levers are connected together by means of a pin 5| which is pivotally connected to one end of a rod 52, the opposite end of which operatively engages the supply valve 25.

For controlling movement of the plunger 45 there is provided a rocking lever 54, which is' journaled on a shaft having the ends thereof rotatably mounted in the casing section I8. The rocking lever 54 is provided with an arm 55 adapted to engage the end of the plunger 45, and has formed on the opposite end thereof a cam face 5?, the purpose of which will herein after appear.

' A lever is carried on the shaft 55 and is keyed thereto by means of a key BI. The lever 60 is provided with a lug 63 which is' adapted toengagean upper surface of the rocking lever 54 for causing said lever to turn with the shaft 55 when the lever 59 is movedin a counterclockwise direction, as viewed in Fig. 2 of the drawings. It will be noted however that the rocking lever 54 is thus adapted to turn in a counterclockwise direction independently of the lever 59 when downward pressure is applied to the came face 57.

As is best shown in Fig. 30f the drawings, the emergency piston section 2! has formed therein a piston chamber E5,'which communicates by way of a passage 6'! with a pipe 58. Operatively mounted in the chamber 65 is an emergency piston I0, having a stem II extending into a bore I2 which opens into the pressure chamber 23. The right-hand endof the stem II is adapted to iengagea piston I3 which is slidably mounted in the bore I2 and has a stem I4 having one end slidably mounted in a guide bushing I5 carried within the casing section 2|.

act against a collar member I8 which engages one of a pair of flanges l9 formedon the stem I4 for urging said stem and the pistons 13 and IQ toward the left-hand or emergency position.

The stem I4 is adapted to control movement of "a? cam member 8!, which is provided within the casing section 2I and has a projecting yoke portion 82 interposed between the flanges I9 on the stem. The cam member 8I has a horizontally disposed tongue 83 formed on the opposite side thereof and slidably fittedwithin a suitable groove provided in a guide block 84, which is-secured to the-casing section i8 within the chamber 23. The,

lower portion of the guide block. 84 has a slot 86 formed therein through which extends the end of the rocking lever 54 carrying the cam face 51,

which is positioned in operative'alignment with an inclined cam face 8? formed on the lower portion hereinafter described to prevent movement of the'piston I9 and cam member 8| controlled thereby into the emergency position. The inter locking means'comprises a bar or pawl 95. one

A pair of springs 11 and 11a is disposed around the bushing I5 and" end of which is pivotally connected by means of a pin 9| to the upper end of the vertically disposed lever 60, as is best shown in Fig. 2 of the drawings, the other end of said pawl being adapted to be moved through a slot 92 formed in the uppermost portion of the guide block 84 and into the path of the cam member 8|. As is best shown in Fig. 4 of the drawings, the free end of the. pawl '95 has formed thereon an in clined cam face 93, which is adapted for engagement with a corresponding cam face 94 formed on the uppermost portion of the cam member BI, when the pawl is moved into the service position as shown in Fig. 4. Aspring 96 is provided for urging-'the'pawl downwardly into engagement with the lower face of the slot 92, one end of this spring being secured to the pawl and the other end of a cable I05, which is secured to the lowerv end of the operating lever as shown in Fig. 1 of the drawings and is controlled by operation of the brake pedal device I5.' Y

According to the invention, means is provided for rendering the interlocking mechanism ineffective to prevent movement of the cam member 8| and associated elements to the emergency position, even after a service application has been made, when the shaft 55 is rotated so as to cause movement of the plunger 46 to its uppermost position for operating the self-lapping valve mechanism to eifect an emergency application of the brakes. In the embodiment of the inventionnow being described, this means comprises a lug 95, which is formed on a portion of the lever member 45 extending beyond the pin 5!, as is best shown in Figs. 2 and 4 of the drawings. The lug 95 is operatively aligned with the pawl 99, and is adapted to engage and to lift said pawl out of the position thereof. It will thus be understood that the lug 95 on the lever 45 is adapted to permit the normal functioning of the pawl 58 so long as the self-lapping valve mechanism is not moved beyond service position, but that continued movement of the brake valve device beyond the service position by manual operation thereof in the manner hereinafter described will cause the lug 95 to raise the pawl 90 against the. tension of the spring 96 so that 'said pawl cannot interfere with subsequent movement of the cam member 8| and the associated elements to the emergency position.

The brake pedal device 55 shown in Fig. 1 com V prises a casing I05 which is adapted to be secured to the floor of the vehicle by any suitable means, not shown. Attached to the casing is a lug I96 carrying apinIIII to which is pivotally connected a bell crank lever I98, one arm of which is connected to the cable I59. The other arm of the bell crank lever I08 is pivotally connected to the lower end of a vertically arranged rod Hi), the

upper end of which extends through'an aperture win the casing I55 and is pivotally connected to a manually operable member I I I. The member III has a portion, II2 extending through an pin II5 carried on one end of a horizontally disposed arm I I6, the other end of which is pivotally connected by means of a pin I I1 to the casing I05. A foot pedal I I9 is secured by any suitable means to the portion I I2 for operating the member I I I. A spring I is interposed between the casing I05 and the arm I I6 and is adapted to urge said arm, the member III and the pedal II9 upwardly.

Contained in a valve chamber I22 formed in a casing section I2I secured to the casing I05 is a vent valve I23, which has a stem I24 extending through a bore in the casing into operative alignment with the arm II6. A spring I25 is interposed between the wall of the chamber I22 and a disk I26 engaging the valve I23, which spring is adapted to maintain the valve seated when the arm II 6, the member III, and the pedal II9 are held in their downward position as shown in the drawings under pressure applied to the pedal by the operators foot. The upper surface ofthe disk I26 engages a supply valve I28, which has a fluted stem I29 mounted in a suitable bore in the casing and is adapted to control communication between the valve chamber I22 and a passage I30 formed in the casing and connected by way of a pipe I3! with the main reservoir I0.

The valve chamber I22 communicates by way of a passage I33 formed in the casing I05 with a chamber I34, which is connected through a bore I35 with a valve chamber I36 communicating with the pipe 68. Communication from the chamber I34 to the valve chamber I36 is controlled by a supply valve I38 having a fluted stem I39 mounted in the bore I35, the supply valve being normally held unseated by the pressure of a spring I40 which is interposed between the wall of the chamber I36 and a collar I4I formed on the valve. A vent valve I42 is mounted in the valve chamber I36 in operative engagement with the valve I38, and is adapted normally to be maintained seated by the pressure of the spring I40 acting through the medium of the valve I38. The vent valve I42 is provided with an upwardly projecting stem I43 that is in operative alignment with an end I44 of the member III and is adapted to be engaged thereby upon movement of said member into an emergency position.

In operation, fluid under pressure supplied in the usual manner to the main reservoir I0 flows through the pipe and passage 21 to the valve chamber 26 in the brake valve device I4, and also is supplied through the pipe I3I, the passage I30 and past the fluted stem I29 to the valve cham ber I22 in the cut-off valve device I 5, it being assumed that the pedal H9 and the associated member-s III and H6 are held in the downward position by the operators foot, as shown in Fig. l. Fluid under pressure thus supplied to the valve chamber I22 flows from that chamber through the passage I33 and chamber I34 and past the normally open valve I38 to the valve chamber I36, and thence flows through the pipe 68 and the passage 61 in the brake valve device I4 to the chamber 66, shown in Fig. 3, so that the pressure of fluid acting against the emergency piston 10 moves said piston, the stem II, the stem 14 and the cam member 8| controlled thereby toward the right-hand to the release position shown in the drawings.

While the pedal III! of the brake pedal device I5 is held in release position as just described, the spring 98 on the brake valve device I4 is permitted to maintain the operating lever 91 in the release position as shown in Fig. 2 of the drawings, the self-lapping valve mechanism being at the same time so positioned that the supply valve: 25 is maintained seated by the spring 20 while the discharge valve 35 is held away from the seat 36 by the spring 30. With the discharge valve 35 unseated, the brake cylinder II communicates with the atmosphere by way of the pipe and passage 24, the pressure chamber 23, the passage 38 in the piston 30 and through the connected chambers 31 and 32 and passage and pipe 33.

If the operators foot is removed from the pedal I I9, the spring I20 is permitted to move the arm H5 and the member III upwardly into the dead mans emergency position, the arm turning about the pivot pin Ill. In so moving, the arm II6 engages the stem I24 and thereby shifts the associated valves I23 and I28 upwardly, overcoming the pressure of spring I25, until the valve I28 is seated and the valve I23 unseated for establishing communication from the chamber I22 to the atmosphere.

With the valve I23 unseated, fluid under pressure is vented to the atmosphere from the emer'-' gency chamber 66 in the brake valve device I4 by way of the passage 61, the pipe 60, chamber I36, past the unseated valve I38 and through the chamber I34, and through the passage I33 and valve chamber I22 and past the unseated valve I23. As the pressure of fluid in the chamber 66 is thus reduced, the springs 11 act through the medium of the collar 18 and the stem 14 to shift the cam member SI to the left, as viewed in Fig.- 3 of the drawings. The inclined cam face 81 of the cam member BI is thereby brought into engagement with the cam face 51 on the rocking lever 54, and continued movement of the cam member then causes said rocking lever to turn in a counterclockwise direction about the shaft 54, as viewed in Fig. 2 of the drawings.

As the rocking lever 54 is thus rotated in a counterclockwise direction, the arm 56 thereof moves the plunger 46 and the associated levers 44 and 45 upwardly. In so moving, the levers 44 and 45 initially act through the medium of the roller 49 and the stem 4I to move the release valve 35 into engagement with the seat 36, overcoming the pressure of the spring 39, it being understood that said spring is somewhat weaker than the spring 28 which urges the supply valve 25 to its seat. With the release valve 35 seated, communication from the chamber 32 and consequently from the brake cylinder to the atmosphere is cut off. The metering spring 3| exerts a greater force than that of the spring 39 and the spring 28 combined, so that continued upward movement of the plunger 46 by rotation of the rocking lever 54 in the manner described causes the levers 44 and 45 to turn about the pin 48 as a fulcrum, thereby moving the stem 52 upwardly so as to unseat the supply valve 25 against the pressure of the spring 28.

With the supply valve 25 unseated, fluid under I pressure is supplied from the main reservoir I0 by way of the pipe and passage 21 and the valve chamber 26 to the pressure chamber 23 and thence through the passage and pipe 24 to the brake cylinder I I. When the pressure of fluid in the chamber 23 slightly exceeds the pressure of spring 3!, the fluid pressure forces the piston 30 upwardly until a stem I43 provided onsaid piston engages a stop member I49 mounted in the brake valve device I4, it being understood that the plunger 46 is at the same time moved to its uppermost or emergency position. The supply valve 25 is thus maintained open so that the brake cylinder II is supplied with fluid at the I 65 pipe 24 to the brake cylinder II.

75 the exhaust valve seated.

maximurnpressure carried in the main reservoir,

thereby eifecti'ng an emergency application of the brakes.

Meanwhile, as the springs 11 and Ila move the stem I4 and the elements associated therewith to the left as shown in Fig. 3, the piston I3 is shifted in the bore I2 to a position in which communication is established between the chamber 23 and a passage I5I formed in the casing of the brake valve device, which passage is connected by way of a pipe I52 with the sanding device I2 and through a pipe I53 with the circuit breaker device I3. Thecircuit breaker device I3 is then operated in the usual manner 'to 'cut off the supply of current to the driving motors of the vehicle, while the sanding device I2, which may be of any desired type, is operated to supply sand to the rails.

In order to effect a release of the brakes fol- "lpwing a dead mans emergency application, the

pedal IIS of the brake pedal device I5 is depressed to the position shown in Fig. 1 so that the valve I23 is seated, while the valve I28 is unseated to permit the supply of fluid under pressure from the main reservoir to the chamber 65 in the brake valve device I4. As fluid at main reservoir pressure is supplied to the chamber 66 as just described, the piston It and the cam member 8| operated thereby are forced towa'rd the 30 right-hand as viewed in Fig. 3, thereby freeing the rocking lever 54, which is then turned in a clockwise direction by the plunger 45- as said plunger and the associated. elements of the selflapping valve mechanism are returned to the release position as shown in Fig. 2 of the drawings.-

If it is desired to effect a service application of the brakes, the brake pedal device I5 is operated through the medium of the pedal I I9 so that .40 the member III and the rod He pivotally connected thereto are moved downwardly, the member III turning about the journal H5. In moving downwardly the rod I I 0 causes the bell crank lever I08 to turn in a counterclockwise direction 45 about the pin I57, thus operating the cable I95 to turn the operating lever 9'! on the brake valve device I4 toward service position. As the shaft 55, shown in Fig. 2, is thus rotated in a counterclockwise direction through the medium of the 50 =lve'r'9'l, the lug 53 carried on the lever 60 keyed on said shaft moves the rocking lever 54 so that the arm 56'thereof forces the plunger 45 upwardly. As the plunger 46 is moved upwardly,

the levers 44 and 45 pivotally carried thereon 55 are first fulcrumed on the pin 5I which is held stationary by the spring 28, the levers thereby moving stem ll until the release valve 35 is moved to its seat, whereupon said levers are turned about the pin 48 as a fulcrum for unseating the supply 60 valve 25. With the supply valve 25 unseated,

70 the supply valve 25 to its seat, the rod 52 being moved downwardly to rock the levers 44 and 45 in a counterclockwise direction about the pin 43.

, Thus the brake valve device isautomatically operated to lap the supply valve while maintaining It willbe noted that during'the operation of the brakevalve device I4=just described, when the shaft 55 is rotated in a counterclockwise" direction the vertically disposed lever 69 secured thereto is operated to' move the pawl 90 toward the left, as viewed in Fig. 2, the cam face 93 of the pawl being thereby positioned in the path of the cam member 8 I, as'isillustrated in Fig. 4.

With the apparatus in service position, the operator may'remove his foot from the pedal I I9 of the pedalvalve device I5 without causing a dead mans emergency application of the brakes. If the operators foot is removed from the pedal H9, the resulting venting offluid under pressure from the chamber 65 in the brake valve device in the manner 'hereinbefore described will permit the springs '11 and 11a to shiftthe stem I4 and the cam member 8| to the left only until said cam' member engages the pawl 95, this movement being insufficient to effect the emergency operation 'of the brake valve device I4.

According to the invention, however, if it is desired to effect an emergency application of the brakes following operation to effect a service application as just described, the operator may move the pedal H9 on the brake pedal device I5 downwardly beyond the service position thereof into an emergency position, wherein the end I44 of the member III is brought into operating engagement with the stem I43 so as to unseat the valve I42 and to seat the valve I33 against the pressure of the spring I;

At the same time, the member I II'moves the rod III} downwardly and operates the bell crank "lever I138, the cable I90, and the operating lever 91' on the brake valve device I4 to rotate the shaft 55 thereof in a counterclockwise direc tion. This movement of the operating arm 91 rotates the shaft 55'beyond the maximum service position thereof, and the rocking lever 54 is consequently operated by said shaft to force the plunger 46 to its uppermost position. As the plunger and the levers 44 and 45 connected thereto are thus moved upwardly beyond their service positions, the lug 95 carried on the arm 45 is brought into engagement with the lower surface of the pawl 95, which is thereupon forced upwardly against the fo'rce'of spring 96, turning,

about'the pinSI, until the cam face 93 of the pawl is moved out of the path of the cam member BI. i

Meanwhile, with theval-ve I42 unseated, fluid under pressure is vented from the chamber 66 in the brake valve device I 4 by way of the passage 61, the pipe 58, the valve chamber I36 in the brake pedal device I5 and past the fluted stem I43 to the atmosphere. Upon the reduction in the pressure of fluid in the chamber 66, the

brake valve device I4 is operative in the manner 'hereinbefore described to effect an emergency application of the brakes.

Itwill now be apparent that the form of the invention just described comprises means adapted to be mechanically actuated upon movement of the brake valve device beyond the service posi-' tion thereof to hold the interlocking bar or pawl. 99 in a position wherein the pawl is ineffective to prevent automatic operation of the brake valve device to emergency position.

Fluid pressure brake apparatus embodying another form of the invention is illustrated in Figs. 5, 6, and 7 of the drawings. The brake valve device shown in Fig. 5 is'substa'ntially the .same in construction and arrangement of its parts as that shown in Fig. 2 ofthedrawings and includes the casing sections II, I8, 20, and

Zia. The casing section 2M is adapted to contain emergency piston mechanism similar to that carr ied within the casing section 2'! 'of Fig.2,

, tion I55.

suitable bore formed in the cylinder portion I56 and in additionis provided with. a cylinder por- A piston i5'l is slidably mounted in a and forms on one side a chamber 'i'iiB which is connected to a pipe IE9. A gasket I66 is inserted in the lower face of the piston I5! and a spring I52 is provided for urging the piston downwardly so that the gasket engages an annular seat member I63 mounted in the cylinder portion, said spring being interposed between the piston I51 and a cap I64 which is secured to the cylinder portion in any suitable manner for closting the chamber E58. The piston I5? is provided with a stem I65, which has screw-threaded connection with said piston and may be secured in position by means of a locking nut N56. The

[lower end of the stem I65 extends into the chamber 23 and has formed thereon an arm i6! that I extends around the guideblock 6'4 and'carries a lug i68 which is normallypositioned beneath and in operative aiign'ment with the pawl 96.

As shown in Fig. '7' or" the drawings; a pedal valve device adapted for contr'olling'operation of the brake valve device shown in Fig. 5 is provided. The pedal valve device comprises 'a casing I70 I having a substantially horizontally disposed lever i'iI mountedthereon by means of a pin I12, the other end of whichlever carries a pin I13 on jwhich is jcurrialed a lever Iii adapted to be ff operated through the medium of a pedal I15.

A rod It? is pivotally connected to the lever I'M by means or a .pin H8, and extends downwardly through an'ape'rture IE9 formed in the casing 9'56, the lower end of the rod being operatively connected to the operating lever 91? on the brake valve shown in Fig. 5 by suitable means, such as the bellerank lever I98 and the cable M36 as shown in Fig. lot the drawings. A spring MI is interposed between the casing I75) and the lever Ill for urging the lever and the associated elements upwardly into a dead mans emergency position,

7 it being understood that in the drawings: the brake pedal device is shown in release position. I

'Contained in a valve chamber I82 formed in a casing section I85 secured to the casing I19 is a vent valve l33 which has afiuted stem I84 extending downwardly in operative alignment A normally 7 the valves I9I and I95 into unseated and seated positions, respectively. The chamber I92 communicates by way of a passage 299 in the easf ing Im with the pipe 69 which leads to the emerc gency'piston chamber in the brake valve device shown in Fig. 5, it being understood that this chamber is the same as that designated at 66 in Fig. 3.

A supply valve 202 and a' vent valve 203 in engagement therewith are provided in a valve chamber 264 which is formed in the casing I19 and communicates through the pipe I 69 with the chamber I58 in the brake valve device shown in Fig. 5 of the drawings. A spring 294 is interposed between the casing and a collar 268 provided on the valve 262 for urging said valve into unseated position, the Vent valve 293 being normaily maintained seated as'shown in Fig '7. The vent valve 293 is provided with a fluted stemm which extends upwardly through a suitable bore in the casing Il9 and is operatively connected'to one end of a yoke 2 by any suitable means, such as the pin 2 !3, the opposite end of the yoke being similarly connected to the upper end of the stem. I96, as by the pin 2I4. The yoke 2| i is adapted to be operatively engaged by the end 2I5 of the lever I14 upon downward movement thereof for operating both sets of valves at the-same time.

With the brake pedal device and the brake valve device in their release positions as shown in Figs. 5 and 7 of the drawings, fluid under pressure is supplied from the main reservoir through the pipe I3I, a branch pipe I3Ia, a

passage ZI'i' in the casing I16, past the unseated supply valve 292, and through the chamber 294 and pipe I59 to the chamber IE6 in the'brake valve device for holding the piston I5? in the position shown in the drawings.

The operation of the apparatus shown in Figs.

5 and 7 of the drawings in the dead mans emer-. gency and service positions thereof will be readily understood from the description hereinbefore presented in connection with the apparatus shown in Fig. 1. Assuming that the pedal I15 is operated so as to move the brake valve device shown, in Fig. 5 into a service position so as to effect the supply of fluid under pressure to. the chamber 23 and the brake cylinder for causing a service application of the brakes, the pawl as is moved in the usual manner toward the left-hand and into the path of the cam member 8|, which isof course held in its release position by the to controlcomm'unication from the valve chamber N32 to a passage 199 connected with the main reservoir by way of pipe ISI.

' lower wall of the chamber I92 and a collar I99 A supply valve I9I is disposed in a valve chamber' I92 formed in the-casing I'iil for controlling communication between that chamber and a chamber I93 which'is connected by way of a pasage I94 formed in the casing with the valve formed on the valve I 9I and is adapted to urge pressure of fluid acting on the emergency piston as hereinbefore described. While the brake pedal device is in service position, communication is maintained from the main reservoir by way of the pipe I3I, branch pipe I3I passage 2I'I, past the unseated supply valve 292, and through the chamber 294 and the pipe I59 to the piston cham- 'ber I58 in the brake valve device, so that the piston -I5'I is held in the position shown in the drawings againstthe opposing pressure fluid at brake cylinder pressure in the chamber 23.

If it is desired to effect an emergency application of the brake following operation of the apparatus into the service position as just described, the pedal I15 on the brake pedal device is moved downwardly beyond the service position, so that the end 2I5 of the lever I14 is brought into operative engagement with the yoke 2H for operating the two pairs of valves associated therewith. The valves I9I and 202 are thereby moved into engagement with their respective seats against the pressures of the springs I91 and 201, respectively, while the vent valves I95 .I5'I exposed to said chamber within the seat I63 is enabled to force the piston upwardly, thereby exposing the full pressure area thereof to the chamber 23. The piston I51 is thereupon moved to its uppermost position with a quick snap-like action, and through the medium of the stem I65 and the arm I61 causes the lug I68 thereon to lift thepawl 90 upwardly against the force of the spring 96. The pawl 90 is thus moved out of the path of the cam member 8|.

At the same time, fluid under pressure is vented from the emergency piston chamber by way of the pipe 68 and through the passage 200 in the pedal valve device shown in Fig. 7, the

valve chamber I92 and past the open vent valve I85 to the atmosphere, so as to permit the usual operation of the cam member BI and the elements associated therewith to the emergency position in the manner already described.

It will thus be apparent that according to the embodiment of the invention just described, means operable by fluid pressure is provided for moving the pawl 90 into a position wherein the pawl is not effective to prevent operation of the brake valve device for causing an emergency application of the brakes, the fluid pressure op erated means being operated only when the brake control pedal is moved beyond a service position by the operator.

While two illustrative embodiments of the invention have been described, in detail, it is not my intention to limit its scope to those emembodiments or otherwise than by the terms of the appended claims.

Having now described my invention, what I claim as new and desire to secure by Letters Patent, is;

1. In a fluid pressure brake, in combination, valve means operative upon movement to a service positionto effect a service application of the brakes and upon a further movement to an emergency position to effect an emergency application of the brakes, automatic means operative upon a reduction in fluid pressure for moving said valve means to the emergency position, manually controlled means for operating said Valve means, locking mechanism operative upon movement of said valve means to service position by the manually controlled means for preventing operation of said automatic means, and means operative when said manually controlled means is operated for moving said valve meansbeyond the service "position to render said locking mechanism ineffective to prevent the operation of the automatic means.

2. In a fluid pressure brake, in combination,

'brakevalve means controlling the application of the brakes and having release, service and emergency positions, automatic means operative for moving said brake valve means to emergency posi- 'tion, manually operable means for operating said brakevalve-means andmovable to: a serviceposi- 3 tion for causing said valve means. to eifect a service application of the brakes, said manually operable'means being operable upon release by the operator for-effecting operation of the automatic means to emergency position, a member associated with said manually operable means adapted to be moved to' a locking position iorl preventing operation of the automatic means when said brake valve means is moved to service position, and meansoperative upon movement of said manually operable means to a position beyond service position to hold said member out of its locking position, H p 7 3. In a fluid pressure brake, in combination, valvemeans operative upon movement to a service position to effect a service application of the brakes and upon a further movement to an emergency position to: effect an emergency ap- 7 plication of the brakes, manually controlled means for'operating said valve means, automatic means operative upon a reduction in fluid pressure for moving said valve means to the emergency position, locking mechanism including a pawl operative by said manually controlled means in moving said valve means to service position to prevent operation of said automatic means, and a member associated with the valve means and actuated upon movement of said valve means beyond thejs ervice position by said manually controlled means to render said pawl inefiectiveto prevent operation of the automatic means. 7

4. Ina fluid pressure brake, in combination, a self lapping brake valve device comprising a supply valve, a discharge valve, a pivotally mounted lever for moving said valves to positions 'for effecting service and emergency applications of the brakesmanually operable means for actuating said lever, automatic emergency mechanismoperativeto move said lever to a position for operating said valves to effect an emergency application of the brakeaa member associated with said manually operable means and biased to a locking position. for preventing operation of said emergency mechanism while said brake valve device is in a service application position,

and a lug carrier by said lever and operatively aligned withsaid member, said lug being operativeupon movement of the lever from'service toward the emergency. position by said manually operablemeans to hold said member out'of the locking position.

5. ma fluid pressure brake, in combination, valve means operativein a service position to effect a service application of thebrakes and on a further movement to an emergencyposition .to eflfect an emergency a zpplication of the brakes,

manually co'ntrolled means for operating said valve meansautomatic means operative upon a reduction in fluid pressure iormoving' said valve means to. the, emergencygposition, locking mechanism including a pawLppe rative' by said Imanii- ,ally: controlled means in moving said valve means to service position toprevent operation of J'said automatic: means, a member "operative to render said pawlineifective to prevent'operation' of the automatic means, and fluid pressure controlled means adapted to operate said member when said manuallypontrolled meansis operated. to move the valve meansbeyond the service position.

6. The combination with a brake valvedevice I comprising self-lapping valve means movable to different positions for supplying and, releasing fluid under pressure to and fronra chamber in effecting the application and release for the brakes, manuallyoperable means for operating said valve means, "automatic emergency'means aoccarii for operating said valve means to effect an emergency application of the brakes, and locking means actuated by the manually operable means in moving the valve means to a service position for preventing operation of said automatic emergency means, of mechanism adapted to render the locking means ineffective When the manually operable means is operated to move the brake valve device from the service position toward the emergency position, said mechanism including a movable abutment operative by the pressure of fluid in said chamber upon a reduction in an opposing pressure.

7. The combination with a brake valve device comprising self-lapping means movable to different positions for supplying and releasing fluid under pressure to and from a chamber in effecting the application and release of the brakes, manually operable means for operating said valve means, automatic emergency means for operating said valve means to effect an emergency application of the brakes, and locking means actuated by the manually operable means in moving the valve means to a service position for preventing operation of said automatic emergency means, of movable abutment means adapted to be operated by the pressure of fluid in said chamber upon a reduction in the fluid pressure in another chamber for rendering said locking means ineffective, and valve means adapted to be actuated by said manually operable means in moving the brake valve device from the service position toward the emergency position thereof to vent fluid under pressure from said other chamber.

8. In a fluid pressure brake, in. combination, brake valve means operative in a service position to effect a service application of the brakes and on a further movement to an emergency position to effect an emergency application of the brakes, automatic emergency means operative upon a reduction in the pressure of fluid in a chamber for moving said brake valve means to the emergency position, a. vent valve operative to vent fluid under pressure from said chamber, and means manually operable through a service zone for operating said brake valve means to effect a service application of the brakes, said means being operative on. further movement thereof beyond the serice zone to actuate said vent valve for venting fluid under pressure from' said chamber.

9. In a fluid pressure brake, in combination, brake valve means operative in a service position to effect a service application of the brakes and on a further movement to an emergency position to effect an emergency application of the brakes, automatic emergency means operative upon a reduction in the pressure of fluid in a chamber for moving said brake valve means to the emergency position, a pair of vent valves adapted to be independently actuated to vent fluid under pressure from said chamber, and manually operable means movable through a service zone for operating said brake valve means to effect a service application of the brakes, said manually operable means being operative When released by the operator for actuating one of said vent valves and when moved to a position beyond the service zone to actuate the other vent valve.

10. In a fluid pressure brake, in combination, brake valve means operative in a service position to effect a service application of the brakes and on a further movement to an emergency position to effect an emergency application of the brakes, automatic emergency means operative upon a reduction in the pressure of fluid in a chamber for moving said brake valve means to the emergency position, manually operable means for operating said brake valve means, locking means actuated by the manually operable means in moving said brake valve means to a service position for preventing operation of said emergency means, means operative upon a re duction in the pressure or" fluid in another chamber to render said locking means ineffective to prevent operation of said emergency means, and valve means adapted to be actuated by said manually operable means in moving the brake valve means from service position toward emergency position to vent fluid under pressure from both of said chambers.

ELLIS E. HEWITT.

CERTIFICATE O CORRECTION. Patent No. 2 ;096,L 9L I October 19, 19 7.

ELLIS E. HEWITT.

It is hereby certified that error appears in' the' printed specification of the above numbered patent reqliiring correction as follows: Page 6, "second column, line 1 .5, claim L for the word "carrier" read carried; and that the said Letters Patent should be read with thz is correction therein that the same may conform to the record of the case in the .Patent Office Signed and sealed this 25th 'dayof January, A. D. 1958.

Henry Van Arsdale, (Seal) Acting Commissibner of Patents, 

